Production of unsaturated nitriles using catalysts promoted with various metals

ABSTRACT

Certain catalysts containing iron, bismuth and molybdenum plus nickel, cobalt, manganese, magnesium, zinc, cadmium or calcium have been found to give especially large volumes of acrylonitrile or methacrylonitrile in a given time when germanium, tin, copper, silver, chromium, ruthenium, titanium, tungsten and/or beryllium are incorporated into the catalyst.

This application is a continuation of Ser. No. 380,527 filed 7/19/73,now abandoned.

BACKGROUND OF THE INVENTION

A number of very desirable ammoxidation catalysts are known whichrepresent the base catalysts of the invention. These catalysts are usedto produce acrylonitrile or methacrylonitrile under certain conditionswith high per pass conversions. Under these conditions, if the amount ofolefin fed over the catalyst in a given time is increased significantly,the per pass conversion tends to drop. In some instances, the per passconversion to unsaturated nitriles drops markedly. Since the viabilityof a commercial operation is significantly affected by the amount ofproduct that can be prepared in a given time, the present invention isdirected at the problem in the art of increasing the production ofproduct in a given time while maintaining high per pass conversions.

SUMMARY OF THE INVENTION

It has now been discovered in the process for the preparation ofacrylonitrile or methacrylonitrile by the reaction of propylene orisobutylene, molecular oxygen and ammonia at a temperature of about 200°C. to about 600° C. in the presence of a catalyst, the improvementcomprising

using as the catalyst a catalyst having the atomic ratios described bythe formula

    X.sub.a A.sub.b C.sub.c Fe.sub.d Bi.sub.e Mo.sub.12 O.sub.x

wherein

X is Ge, Sn, Cu, Ag, Cr, Ru, Ti, W, Be or mixture thereof;

A is an alkali metal, alkaline earth metal, rare earth metal, Nb, Ta,Tl, P, As, B, Sb or mixture thereof;

C is Ni, Co, Mg, Mn, Zn, Cd, Ca or mixture thereof; and

wherein

a is 0.01 to about 4;

b is 0 to about 4;

c and d are 0.01 to about 12;

e is 0.01 to about 6; and

x is the number of oxygens required to satisfy the valence requirementsof the other elements present.

The process of the present invention provides a commercially feasibleprocess for preparing large quantities of acrylonitrile ormethacrylonitrile in a given period of time at high per passconversions.

The amount of a desirable acrylonitrile or methacrylonitrile produced inan ammoxidation reaction is essentially a function of (1) the amount ofolefin fed to the reactor in a given period of time, and (2) the perpass conversion to the desired product. As noted above, catalysts usefulin ammoxidation reactions have been limited to a certain range of feedrates to provide high per pass conversions. When higher feed rates areattempted, the per pass conversion drops and the reaction becomes lessefficient. When lower feed rates are employed, less of the desiredproduct is produced. The present invention solves this problem by thediscovery of catalysts that can accept a high reactant feed rate whileat the same time maintain a high per pass conversion.

The reactant feed rate is normally stated as "WWH" and is measuredaccording to the following formula: ##EQU1## It can be seen from theformula that the rate of reactant feed varies directly with the WWH--asthe WWH increases, the rate of reactant feed increases.

The second variable is the per pass conversion. Per pass conversion isusually stated in terms of mole percent of a product formed according tothe following formula for acrylonitrile. ##EQU2## It is seen that theamount of product formed is a direct function of the per passconversion.

The central aspect of the present invention is the catalyst employed.The catalyst is suitably any catalyst containing the elements describedin the formula above. Broadly, the base catalysts contain at least iron,molybdenum and bismuth and at least one of nickel, cobalt, magnesium,manganese, zinc, cadmium or calcium. In addition to these base elements,there is a large number of optional elements that could be incorporatedinto the catalyst. These base catalysts of the invention are knowncatalysts useful for ammoxidation reactions. Accordingly, the basecatalyst and its preparations are not the subject of the presentinvention even though there are preferred variations in the basecatalyst.

The present invention is the incorporation of germanium, tin, copper,silver, chromium, ruthenium, titanium, tungsten, beryllium or mixturethereof into the base catalyst to provide higher rates of production athigh per pass conversions.

The elements added to the base catalyst can be incorporated into thecatalysts in any amount that is effective to obtain improved results ofthe present invention. Although this range may vary, a preferred rangeof 0.01 to about 4 is designated in the general formula. A morepreferred range is about 0.1 to about 2.

Although a mixture of germanium, tin, copper, silver, chromium,ruthenium, titanium, tungsten and beryllium could be used, it ispreferred to use each of these elements separately in the catalyst. Inthe catalyst formula, this is accomplished by separately setting X equalto each of these elements.

The base catalyst to which the promoter elements are added also haspreferred embodiments. Preferred are catalysts that contain nickel orcobalt or mixtures thereof, i.e. wherein C is nickel, cobalt or mixturesthereof. Also preferred are catalysts that contain an alkali metal,especially potassium.

The catalysts of the invention are suitably used in supported orunsupported form. Representative examples of carrier materials includesilica, alumina, zirconia, titanium dioxide, boron phosphate and thelike.

The reactants, process conditions and other reaction parameters of thereaction are known in the art of the ammoxidation of propylene andisobutylene. The conditions, reactors and the like are not substantiallychanged from the art. The temperature may range from about 200° to about600° C. with about 300° to about 500° C. being preferred. The reactionmay be conducted in a fluid or a fixed-bed reactor using atmospheric,subatmospheric or superatmospheric pressure. A feasible commercialapplication could be use of the present invention in a fluidized-bedreactor at superatmospheric pressure.

Since the present invention is primarily designed to feed more olefinover a catalyst in a given time, it is understood that the feed ratesand composition of the feed could be altered from the art. Expressed interms of WWH, the feed of olefin over the catalyst is preferably betweenabout 0.05 and about 0.25.

Using the present invention, large quantities of acrylonitrile ormethacrylonitrile are produced at high olefin feed rates and high perpass conversions.

SPECIFIC EMBODIMENTS Comparative Examples A & B and Examples1-27--Comparison of catalyst containing promoters of invention with basecatalyst

A 5 cc. fixed-bed reactor was constructed of an 8 mm. inside diameterstainless steel tube. Catalysts prepared as described below were chargedto the reactor and heated to 420° C. under a flow of air. At thereaction temperature for Comparative Example B and Examples 1-27, areactant composition of propylene/ammonia/oxygen/nitrogen/steam of1.8/2.2/3.6/2.4/6 was fed over the catalyst at a contact time of 3seconds. The WWH for the reaction was 0.10.

For Comparative Example A, a reactant feed ofpropylene/ammonia/oxygen/nitrogen/steam in the ratio of 1/1.1/2.1/7.9/4was used at a temperature of 420° C. A contact time of 6 seconds wasused. The WWH was 0.03. This example is included to show a base catalystoperating under normal operating conditions at a low WWH.

The catalysts were prepared as follows:

Comparative Examples A and B 80% K₀.1 Ni₂.5 Co₄.5 Fe₃ BiP₀.5 Mo₁₂ O_(x)+20% SiO₂

A solution of 127.1 g. ammonium heptamolybdate (NH₄)₆ Mo₇ O₂₄.4H₂ O andwater was prepared. To this solution was added 6.9 g. of a 42.5%solution of H₃ PO₄ and 102.7 g. of Nalco 40% silica sol to form aslurry. Separately, an aqueous solution containing 72.7 g., ferricnitrate, Fe(NO₃)₃.9H₂ O; 29.1 g. bismuth nitrate, Bi(NO₃)₃.5H₂ O; 78.6g. cobalt nitrate Co(NO₃)₂.6H₂ O; 43.6 g. nickel nitrate, Ni(NO₃)₂.6H₂O, and 6.1 g. of a 10% potassium nitrate solution was prepared. Thesolution of metal nitrates was slowly added to the slurry. The resultingslurry was evaporated to dryness, and the solid obtained was heattreated at 290° C. for three hours, at 425° C. for three hours and at550° C. for 16 hours.

EXAMPLE 1 80% Ge₀.6 K₀.1 Ni₂.5 Co₄.5 Fe₃ BiP₀.5 Mo₁₂ O_(x) + 20% SiO₂

63.56 Grams of ammonium heptamolybdate was dissolved in 60 cc. of warmwater. This solution was added to 53.25 g. of Nalco 40% silica sol. Themixture was heated at low heat with constant stirring for about 5minutes. To the slurry formed, 3.46 g. of H₃ PO₄ as a 42.5% solution wasadded, and the mixture was heated for 2 minutes.

Separately, 36.36 g. of ferric nitrate was mixed with 10 cc. of waterand melted on a hot plate with constant stirring. Sequentially 14.55 g.bismuth nitrate, 39.29 g. cobalt nitrate, 21.80 g. of nickel nitratewere added, always waiting until the previous metal nitrate had melted.3.03 Grams of KNO₃ added as a 10% solution was combined, and 1.88 g. ofGeO₂ was added and melted.

The solution containing metal nitrates was added slowly to the slurryand heating was increased until the mixture started to thicken. Themixture was dried in an oven at 120° C. with occasional stirring. Thedried catalyst was calcined at 550° C. for 16 hours.

EXAMPLES 2-27

The other catalysts of the examples were made in an identical manner tothe catalysts of Example 1. Germanium, tin, chromium and titanium wereadded to the catalysts as the oxides. Copper and silver were added tothe catalysts as the nitrates. Ruthenium and beryllium were added to thecatalysts as the chlorides. Tungsten was incorporated into the catalystas ammonium tungstate added along with the ammonium heptamolybdate.Although different anions were used, the particular anion of thecatalytic component is not deemed to be critical.

In those catalysts not containing phosphorus, the promoter elements ofthe invention were added to the catalyst through themolybdenum-containing slurry.

The results of the experiments in the ammoxidation of propylene toproduce acrylonitrile are shown in the Table. The parentheses used inthe Table have no significance other than to emphasize the differencesin the catalysts.

                  Table I                                                         ______________________________________                                        Preparation of Acrylonitrile                                                  Comparison of Catalysts of Invention                                          With Base Catalyst                                                                                           Molar Per                                                                     Pass                                           Ex-                            Conver-                                        ample Active Ingredients of Catalyst                                                                         sion, %                                        ______________________________________                                        Comp.                                                                         A     (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5 Mo.sub.12               O.sub.x)                 80.1*                                          Comp.                                                                         B     (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5 Mo.sub.12               O.sub.x)                 73.1                                           1     Ge.sub.0.6 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       80.7                                           2     Ge.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       76.4                                           3     Sn.sub.0.5 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       75.7                                           4     Sn.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       75.0                                           5     Cu.sub.0.1 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       77.9                                           6     Ag.sub.0.1 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       74.2                                           7     Cr.sub.0.5 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       78.3                                           8     Ru.sub.0.1 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       76.4                                           9     Ti.sub.0.5 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       74.3                                           10    Be.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiP.sub.0.5              Mo.sub.12 O.sub.x)       75.0                                           11    Cu.sub.0.1 Ge.sub.0.6 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3               BiP.sub.0.5 Mo.sub.12 O.sub.x)                                                                         76.2                                           12    Ag.sub.0.1 Ge.sub.0.6 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3               BiP.sub.0.5 Mo.sub.12 O.sub.x)                                                                         75.4                                           13    Ru.sub.0.1 Ge.sub.0.6 (K.sub.0.1 Ni.sub.2.5 co.sub.4.5 Fe.sub.3               BiP.sub.0.5 Mo.sub.12 O.sub.x)                                                                         79.3                                           14    Cu.sub.0.1 B.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3                BiP.sub.0.5 Mo.sub.12 O.sub.x)                                                                         76.7                                           15    Ag.sub.0.1 B.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3                BiP.sub.0.5 Mo.sub.12 O.sub.x)                                                                         75.8                                           16    Ru.sub.0.1 B.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3                BiP.sub.0.5 Mo.sub.12 O.sub.x)                                                                         76.5                                           17    Cr.sub.0.6 W.sub.0.6 (K.sub.0.1 Ni.sub.2.5 Co.sub. 4.5 Fe.sub.3               BiP.sub.0.5 Mo.sub.10.8 O.sub.x)                                                                       73.7                                           18    Ge.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.2 BiP.sub.0.5              Mo.sub.12 O.sub.x)       79.1                                           19    Cr.sub.0.5 Ge.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.2               BiP.sub.0.5 Mo.sub.12 O.sub.x)                                                                         79.2                                           20    Sn.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.2 BiP.sub.0.5              Mo.sub.12 O.sub.x)       76.6                                           21    W.sub.0.5 Ge.sub.1.0 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.2                BiMo.sub.12 O.sub.x)     78.4                                           22    Cr.sub.0.5 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12              O.sub.x)                 79.5                                           23    W.sub.0.5 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12               O.sub.x)                 81.6                                           24    Ti.sub.0.5 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12              O.sub.x)                 78.6                                           25    Cu.sub.0.1 B.sub.0.5 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3                BiMo.sub.12 O.sub.x)     80.2                                           26    Sn.sub.0.5 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12              O.sub.x)                 80.6                                           27    Ge.sub.0.5 (K.sub.0.1 Ni.sub.2.5 Co.sub.4.5 Fe.sub.3 BiMo.sub.12              O.sub.x)                 79.1                                           ______________________________________                                         *WWH is 0.03                                                             

Thus, it is seen from the examples above that high per pass conversionsat high WWH values are obtained using the catalysts of the invention.

Example 28 and Comparative Examples C and D--Ammoxidation of Isobutylene

Fresh catalyst of Comparative Example A was used to preparemethacrylonitrile using isobutylene in the feed. In Comparative ExampleC, a feed of isobutylene/ammonia/air/H₂ O of 1/1.2/11/4 was used to shownormal operating conditions, and in Comparative Example D, a feed ofisobutylene/ammonia/oxygen/nitrogen/H₂ O of 1.8/2.2/3.6/2.4/6 showsoperation at high WWH. In Example 28, the catalyst of Example 23 was rununder the same conditions as Comparative Example D. The per passconversion to methacrylonitrile for Comparative Example C was 67.1%; forComparative Example D, 59.3%; and for Example 28, 68.1%. Thus, highyields of methacrylonitrile are obtained using the catalysts of theinvention at a high WWH.

Examples 29-31 and Comparative Example E--Additional calcination at 600°C.

Fresh catalyst of Comparative Example A was calcined at 600° C. for anadditional three hours and run as Comparative Example E under theconditions of high WWH of Comparative Example D. Fresh catalyst ofExamples 22, 23 and 26 were also calcined at 600° C. for threeadditional hours and used to prepare methacrylonitrile under the sameconditions. These results are given in Table II.

                  Table II                                                        ______________________________________                                        Ammoxidation of Isobutylene to                                                Methacrylonitrile at High WWH                                                                          Per Pass Conversion                                  Example                                                                              Catalyst + 3 hr. at 600° C.                                                              to MAN, %                                            ______________________________________                                        Comp. E                                                                              Comparaive Example A                                                                            59.9                                                 29     Example 22        62.1                                                 30     Example 23        65.4                                                 31     Example 26        67.0                                                 ______________________________________                                    

Examples 32-33--Ammoxidation of isobutylene at low WWH

The catalysts of Examples 30 and 31 were run under the conditions of lowWWH of Comparative Example C. The catalyst of Example 30 gave a per passconversion to methacrylonitrile of 71.1%, and the catalyst of Example 26gave a per pass conversion to methacrylonitrile of 74.0%.

We claim:
 1. A catalyst having the following formula:

    X.sub.a A.sub.b D.sub.c Fe.sub.d Bi.sub.e Mo.sub.12 O.sub.x

wherein X is Ge, Ag, Cr, Ru, Ti, W or mixture thereof; A is an alkalimetal, alkaline earth metal, rare earth metal, Nb, Ta, Tl, P, As, B, Sbor mixture thereof; D is Ni, Co, Mg, Mn, Zn, Cd or mixturethereof;wherein a is 0.01 to about 4; b is 0 to about 4; c and d are0.01 to about 12; e is 0.01 to about 6; and x is the number of oxygensrequired to satisfy the valence requirements of the other elementspresent; andwherein said catalyst contains at least one of the followingelement combinations: Cr++ W, Ge+ W, Cr+ P and Ge+ P.
 2. The catalyst ofclaim 1 wherein said catalyst contains Cr+ W.
 3. The catalyst of claim 1wherein said catalyst contains Ge+ W.
 4. The catalyst of claim 1 whereinsaid catalyst contains Cr+ P.
 5. The catalyst of claim 1 wherein saidcatalyst contains Ge+ P.
 6. A catalyst having the following formula:

    X.sub.a A.sub.b D.sub.c Fe.sub.d Bi.sub.e Mo.sub.12 O.sub.x

wherein X is Ge, Sn, Cu, Ag, Cr, Ru, Ti, W or mixtures thereof; A isalkali metal, alkaline earth metal, rare earth metal, Nb, Ta, Tl, P, As,B, Sb or mixtures thereof; D is Ni, Co, Mg, Mn, Zn, Cd or mixturesthereof; andwherein a is 0.01 to about 4; b is 0 to about 4; c and d are0.01 to about 12; e is 0.01 to about 6; and x is the number of oxygensrequired to satisfy the valence requirements of the other elementspresent; andwherein X and A are so selected that said catalyst containsat least one system selected from the group consisting of Cu+ B, Cu+ Geand Cu+ P.
 7. The catalyst of claim 6 wherein said catalyst contains Cu+B.
 8. The catalyst of claim 6 wherein said catalyst contains Cu+ Ge. 9.The catalyst of claim 6 wherein said catalyst contains Cu+ P.